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1.1.1 1,2-Dihydroxylation of Alkenes

DOI: 10.1055/sos-SD-201-00002

Muñiz, K.Science of Synthesis: Stereoselective Synthesis, (201115.

Direct dioxygenation of alkenes represents a standard process for alkene oxidation. By far the most important example of this type of transformation is the osmium(VIII) oxide catalyzed dihydroxylation.[‌1‌] This reaction is usually of excellent selectivity as the osmium reagent displays excellent chemoselectivity with respect to the oxidation of alkenes. This has led to a series of protocols for direct 1,2-dihydroxylation of alkenes. While early protocols were stoichiometric in metal oxidant and hence are no longer in use,[‌2‌] the reaction has benefited significantly from the introduction of co-oxidants. Use of hydrogen peroxide, sodium hypochlorite, and, in particular, 4-methylmorpholine N-oxide as in the Upjohn Process,[‌3‌] and potassium hexacyanoferrate(III)[‌4‌] have proven to be important to this end. An overview of more common oxidants is available.[‌2‌] In principle, osmium(VIII) oxide is capable of converting all kinds of mono-, di-, and trisubstituted alkenes into the corresponding vicinal diols. In several cases, tetrasubstituted alkenes are also found to react. Given the mentioned high selectivity of osmium(VIII) oxide toward C=C bond oxidation, functional-group tolerance is usually not a problem associated with these reactions.

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